Photoinhibiting via simultaneous photoabsorption and free-radical reaction for high-fidelity light-based bioprinting

Light-based 3D bioprinting is now employed widely to fabricate geometrically complex constructs for various biomedical applications. However, the inherent light scattering defect creates significant challenges in patterning dilute hydrogels to form high-fidelity structures with fine-scale features. Herein, we introduce a photoinhibiting approach that can effectively suppress the light scattering effect via a mechanism of simultaneous photoabsorption and free-radical reaction. This biocompatible approach significantly improves the printing resolution (~1.2 - ~2.1 pixels depending on swelling) and shape fidelity (geometric error less than 5%), while minimising the costly trial-and-error procedures. The capability in patterning 3D complex constructs using different hydrogels is demonstrated by manufacturing various scaffolds featuring intricate multi-sized channels and thin-walled networks. Importantly, cellularised gyroid scaffolds (HepG2) are fabricated successfully, exhibiting high cell proliferation and functionality. The strategy established in this study promotes the printability and operability of light-based 3D bioprinting systems, allowing numerous new applications for tissue engineering.

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March 2021
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The data supporting the findings of this study are available in the paper and the Supplementary Information, and can be obtained upon request from the corresponding author fchen@hnu.edu.cn. Source data are provided together with this paper.
Human research participants were not involved in this study.
Human research participants were not involved in this study.
Human research participants were not involved in this study.
Human research participants were not involved in this study.
No statistical method was used to determine the sample size. Sample size was chosen based on previous experience and standards in the field. A minimum of three independent experiments for the majority of conditions. All sample sizes, statistical analysis, and P-value were indicated in the manuscript and No data were excluded from the analysis.
All the printouts for each experiment are not less than three. 90% -100% attempts were successful, depending on the geometric complexity, machine conditions and operational environment.
The imaging of all printed and cultured samples was randomly allocated.
The cell samples were allocated to hydrogel materials in a single-blind approach. The persons performing sample preparation were aware of the identity of hydrogel materials, but unaware of the identity of cell groups. All data have been documented and are available from the corresponding authors upon reasonable request.

March 2021
Materials & experimental systems The PC-12 cells (from Procell Life Science&Technology Co., Ltd, China) separated from the pheochromocytoma of of adrenal gland of SD rats were cultured and a cell line was established in vitro. The HepG2 cells (from Procell Life Science&Technology Co., Ltd, China) were isolated from a hepatocellular carcinoma of of a 15-year-old, White, male youth with liver cancer.
The morphologies of of PC-12, HepG2 were authenticated at at the time of of purchase.
The cell line has been tested negative for mycoplasma contamination.
The cell used in in the research are not presented in in the ICLAC register.